1. Field of the Invention
This invention relates generally to sensors utilizing injection molded flexible dome-caps such as are used in the prior art as simple momentary-On electrical switches. The present invention is specifically directed toward new uses of elastomeric flexible injection molded dome-cap sensors, specifically using such devices in a novel manner as analog sensors.
2. Description of the Related Prior Art
Elastomeric or flexible injection molded dome-cap momentary-On switches (sensors) are well known and widely used in the prior art as switches incorporated in such common host devices as remote controls for televisions and stereos, and in electronic game control devices such as game pads for Nintendo, Sony and Sega game consoles, and some computer keyboards, etc. In all of the above mentioned host devices and in all known prior art where the elastomeric dome-cap sensor is employed, the injection molded dome-cap is always used as a component of a sensor having a single threshold serving as a simple make or break (closed or open) electrical switch in a circuit.
The term elastomeric is used to describe any rubber-like material, whether natural or synthetic.
Structurally, the prior art elastomeric injection molded dome-cap carries a normally raised conductive element or disk referred to as a pill or a carbon pill. The conductive pill is herein sometimes referred to as the xe2x80x9cactive elementxe2x80x9d. The active element in prior art elastomeric injection molded dome-cap sensors is believed to be made of a binder of elastomeric or rubbery material binding carbon or carbon containing material and possibly other materials. The active element is located at the top inside of the non-conductive elastomeric dome-cap and above two proximal highly conductive elements or traces so that with depression of the dome-cap, such as with pressure applied by a finger, the active element is moved with the collapsing dome-cap into contact with both proximal conductive elements and closes an otherwise normally open circuit. Since the injection molded dome-cap is resilient, with release of pressure on the dome-cap it returns to a raised position carrying the active element with it to open the circuit. Electronic circuitry associated with the two proximal conductive elements, which are either bridged or not bridged by the active element of the elastomeric dome-cap, is circuitry which in the prior art has always been structured only to detect or read a threshold event, i.e., an open or closed (binary) state across the proximal conductive elements.
As those skilled in the art appreciate, most, but not all elastomeric injection molded dome-caps when depressed produce a soft snap which is a user discernable tactile feedback. This tactile feedback occurs when the dome-cap is depressed beyond a given point; the point being where a mechanical threshold is crossed and the tactile snap is produced. The snap defining the tactile sensation occurs just prior to the active element being brought into contact with the two proximal conductive elements. The tactile sensation is perceived by the user as occurring at the same time the sensor is activated, which in the prior art is when the switch is closed. The switch remains closed until such time as the user releases pressure on the dome-cap, at which time the dome-cap being made of elastomeric material returns to a raised position carrying the active element with it and off of the proximal conductive elements. The elastomeric injection molded dome-cap typically again produces a tactile sensation as it moves upward crossing the mechanical snap-through threshold. Elastomeric injection molded dome-caps are typically molded or are made primarily of thermoset rubber, are one-piece absent joints or seams, and provide excellent durability for a very low cost. The active element in the prior art is typically adhered to the inside top of the dome-cap during the injection molding phase of manufacturing the dome-cap.
Another type of prior art sensor is described in U.S. Pat. No. 3,806,471 issued Apr. 23, 1974 to R. J. Mitchell for xe2x80x9cPRESSURE RESPONSIVE RESISTIVE MATERIALxe2x80x9d. Mitchell describes sensors which utilize pressure-sensitive variable-conductance material to produce analog outputs. Mitchell does not use or suggest an elastomeric injection molded dome-cap used to either carry variable-conductance material or to transfer finger applied pressure into variable-conductance material. Mitchell also fails to recognize any need for or suggest the use of an elastomeric injection molded dome-cap to provide tactile feedback to the user upon actuation or de-actuation of the pressure-sensitive variable-conductance sensor. U.S. Pat. No. 4,315,238 issued Feb. 9, 1982 to F. Eventoff describes a pressure-sensitive bounceless switch absent a suggestion of using an elastomeric injection molded one-piece dome-cap or providing tactile feedback, and is thus considered to be cumulative prior art to the Mitchell disclosure.
There have been hundreds of millions of momentary-On elastomeric dome-cap style switches made and sold in the last 20 years. Pressure-sensitive variable-conductance sensors have also been known for decades and have always been quite expensive compared to elastomeric injection molded dome-cap switches. The prior art does not suggest the use of an inexpensive elastomeric injection molded dome-cap containing any pressure-sensitive variable-conductance material in association with circuitry structured for control or manipulation by the elastomeric dome-cap sensor applied as an analog sensor, or as a pressure-sensitive variable-conductance sensor which includes tactile feedback in association with circuitry structured for control or manipulation by the elastomeric dome-cap sensor applied as an analog sensor. Clearly an inexpensive injection molded elastomeric dome-cap pressure-sensitive variable-conductance sensor would be useful and of benefit, as also would be such a sensor having tactile feedback. Such sensors would be useful in a wide variety of applications wherein human input is required. Such applications include home electronics, computers and generally, but not limited to, devices operated by the human hand/finger inputs.
I have discovered, as will be detailed below, that a typical elastomeric injection molded dome-cap type switch when used as part of a novel structural combination or in a novel method fills a long standing need for a very inexpensive and durable pressure-sensitive variable-conductance sensor, and further one which can, if desired, supply tactile feedback.
The following detailed description is of best modes and preferred structures for carrying out the invention, and although there are clearly some changes which can be made to that which is specifically herein described and shown, for the sake of briefness of this disclosure, all of these changes which fall within the scope of the present invention have been not herein detailed, but will become apparent to those skilled in the art with a study of this disclosure. The specifications of my pending and allowed U.S. patent applications Ser. No. 09/122,269 filed Jul. 24, 1998, Ser. No. 08/942,450 filed Oct. 1, 1997, and Ser. No. 08/677,378 filed Jul. 5, 1996 are all herein incorporated by reference.
The prior art dome-cap sensors as described above have been always used as simple On/Off switches or bounceless On/Off switches in associated circuitry structured to use the sensor only as a switch. I have discovered that the active element of such prior art dome-cap sensors is pressure-sensitive and variably conductive to a useful degree, and this property of the active element can be used not only as a bounceless switch, but much more importantly as an analog or variable pressure sensor. With applied varying pressure changes, the active element changes it""s conductivity, i.e., resistivity, relative to the applied pressure. The active element, while a moderate to poor conductor when not under compressive force, drops in resistivity when placed under compressive force, such drop in resistivity being related to the amount of compression of the active element. This pressure-sensitive variable-conductance aspect of the active element in the elastomeric injection molded one-piece dome-cap opens many new and valuable possibilities of use.
Such new possibilities include very low cost pressure-sensitive variable-conductance sensors allowing integration into a multitude of price sensitive consumer electronic items. In the past, variable-conductance sensors incorporated into consumer electronic devices were relatively expensive potentiometers and sliding plate resistors, or pressure-sensitive sensors which have typically been even more expensive, running from a few dollars and upward per sensor, and thus such pressure-sensitive sensors are sparingly used. On the other hand, elastomeric dome-cap sensors are currently manufactured in very high volume for a very low cost.
The elastomeric injection molded dome-cap provides an extremely low cost member capable of serving multiple functions all of which can be advantageous and beneficial for a pressure-sensitive variable-conductance sensor. Such multiple functions of the elastomeric one-piece injection molded dome-cap can include: the dome-cap serving as an inexpensive return spring for ensuring termination of pressure on the active element; the top exterior of the dome-cap providing a finger engagement surface when properly fashioned for serving as a finger placement surface on which a user can press absent a requirement of additional button caps or triggers atop the dome-cap; a seal or debris excluder over electric component surfaces which could be adversely affected by the entrance of foreign matter; tactile feedback to the user upon actuation and de-actuation of the active element or sensor; an ergonomically correct depressible surface which is variably depressible through a wide range, generally absent an uncomfortable hard-stop at the bottom of the depressive stroke; and the injection molded dome-cap providing these functions can be mounted on various base materials such as flexible membrane circuit sheets, rigid circuit boards and flexible membranes supported or stiffened by rigid boards which can themselves possess circuitry.
Additionally, the injection molded dome-cap can be manufactured in multiple dome-caps in a single injection molded sheet wherein all of the dome-caps can be utilized as novel pressure sensors or some of the dome-caps can be novel pressure sensors mixed with other dome-caps used as traditional momentary-On switches. Such multiple dome-cap sheets can be highly useful in devices such as television, and the like, remote control devices wherein many functions may be best served with momentary-On switches while other functions (e.g. channel and/or volume scrolling buttons) can be best served with variable-conductance pressure sensors, preferably using the teachings herein.
Durable and low cost pressure-sensitive analog sensors would be of benefit in many host devices to offer the user increased control options, the ability to variably increase and reduce the sensor output dependant on pressure exerted by the user to the dome-cap so that, for example, images may selectively move faster or slower on a display, timers, settings within a range, adjustments and the like may change faster or slower dependant on the pressure applied by the user.
Another benefit of the use of my discovery is in game pads of the type which traditionally have elastomeric dome-cap sensors used only as momentary-On sensors, but with the present invention, the user can press harder to make a controllable character jump higher or run faster for example.
Another benefit of the use of my discovery is in mouse type computer control devices which may have a two or four way rocker for scrolling windows. These currently existing mouse controllers utilize momentary-On switches, some being elastomeric dome-caps, and all would be greatly advantaged with use of the novel analog dome-cap sensors described herein.
Another benefit of the use of my discovery is in keyboard type computer control devices which may have a two or four way rocker, or independent keys, for scrolling windows. Such a novel computer keyboard would be greatly advantaged with use of the novel analog dome-cap sensors described herein.
Another benefit of the use of my discovery is in joystick type devices having buttons and/or trigger on the handle. Such buttons and/or trigger, which in the prior art are momentary-On switches, can be benefited by implementation of the present invention.
Another benefit of the use of my discovery is in ease of changeover by manufactures who currently make host devices including housings with circuit boards therein, elastomeric dome-cap sensors associated with the circuit boards, openings through the housings to allow access to the dome-caps to allow depression thereof, and in some cases button and/or trigger style covers over the injection molded dome-caps. In order to gain the benefit of the present invention, such manufacturers will only need to apply new or modified circuitry on the circuit boards capable of reading any one of at least three readable states (electric states) or many more of the dome-cap sensor indicative of at least three states of the dome-cap and active element which can represent at least: 1) no pressure thereon, 2) low pressure and 3) high pressure applied to the dome-cap and thus the active element. Preferably, the dome-cap sensor will be employed in a manner wherein not just three but many states are read, thus ensuring high resolution reading of a variably changing input.
For the purposes of this disclosure, plural states in reference to the prior art means two states only, typically being On or Off since the dome-cap sensors are used only as On/Off switches in the prior art, and in reference to the present invention, plural states is three or more states as will be further detailed.
Yet another benefit of the use of my discovery is that not only can a typical prior art dome-cap style switch be used as a pressure-sensitive variable-conductance sensor, but if desired, such a sensor can also supply the user with a tactile feedback on actuation of the sensor, and even further upon de-activation of the sensor. Benefits of the tactile feedback include a reduction of potential confusion on the part of the user as to when the sensor is actuated and de-actuated. For example, if an analog sensor or sensor used as an analog sensor of the type not having tactile feedback is minimally activated, it is difficult for the user in some instances to determine whether the sensor is still minimally activated or is entirely de-activated. If the user is playing an electronic game utilizing a variable pressure analog sensor to control movement as he slowly approaches the edge of a cliff which he might fall off of, and the user desires to get very close to the edge but not fall off, the user would be depressing very lightly on the sensor, and absent tactile feedback would not be immediately aware when he inadvertently decreased the depression enough to fully deactivate the sensor.
These, and other advantages and benefits of the present invention will become increasingly appreciated with continued reading and a review of the included drawings.